When driving a vehicle for long intervals of time, especially a truck or heavy equipment, discomfort of the back is evident within the first few hours of driving. This is often referred to as "back fatigue" or "back strain". Some truck drivers find it beneficial to insert a small pillow between the seat back and the small of the back. While this alleviates a considerable amount of the back strain, the cushion never seems to be the proper size or the proper thickness, so this use of a cushion is considered a partial solution to the back fatigue problem.
Schrieber, U.S. Pat. No. 3,052,236, discloses a spinal column supporter having a rearwardly directed seal chamber which is filled with cushion material such as gaseous fluid or liquid fluid. Bell, U.S. Pat. No. 3,181,689; Martinez, U.S. Pat. No. 1,634,621; Boone, U.S. Pat. No. 2,412,075; Norman, U.S. Pat. No. 3,087,496; Draves, U.S. Pat. No. 1,924,640; Johnson, U.S. Pat. No. 3,717,143; Rosenburg, U.S. Pat. No. 4,175,553; Swift, U.S. Pat No. 3,434,469; Berkerly, U.S. Pat. No. 4,080,962; and Gaylord, Jr., U.S. Pat. No. 3,568,670 suggest various different back supports which circumferentially enclose the body and supports the back. However, none of these prior art references provide a back support means by which the supported area at the small of the back can be changed in a manner to effect varying degrees of support without having to change the construction of the pads or the like.
Romano, U.S. Pat. No. 4,135,503, discloses a wide belt having fastening means thereon, with there being a support means 12 in the form of a pocket 14 which can adjust predetermined portions of the spine. A bladder 36, FIG. 5, is comprised of two separate members which are movable respective to a base plate 40, and which can be inflated or deflated by means of a pump 75 and 76. Hence, the Romano device must be manually inflated and deflated by the employment of a pump apparatus.
Eichler, U.S. Pat. No. 4,245,628, discloses a support pad 1 having a fastening plate 9 and arch rib plate 11 to which there is mounted an intermediate foam cushion 12.
The present invention differs from the above recited art by the provision of a back support especially suited for bracing and supporting the spinal column at the small of the back by the employment of a novel variable chamber arranged centrally respective to the small of the back, and held into an optimum position by a circumferentially extending belt which snuggly positions a back panel in a manner to locate the cushion within the small of the back. The cushion can be varied in thickness by the wearer without removing the back support, and without the use of a manually operated air pump.